State looking for answers after power outage

NSTAR president explains Back Bay incident

NSTAR President Craig Hallstrom Monday explained step by step how Sunday’s power outage happened, but some said they are still missing key answers.

The location of the Scotia Street substation is in the heart of Back Bay, which a half dozen large hotels, the Prudential Center and the Hynes Convention Center call home.

Hallstrom said the same transformer that caught fire in March 2012, leaving thousands of customers without power for days, was the source of Sunday’s outage.

The transformer was rebuilt six months ago, and NSTAR was working on its backup unit in the same substation when a cable malfunctioned.

With the backup unit out of service, NSTAR routed power from a substation near Chinatown through a new system installed since March 2012 to get most of the Back Bay up and running by 10 a.m. Sunday, about seven hours after the outage began.

Hallstrom said he did not know why the cable to the newly-built transformer failed. But the state Department of Public Utilities said it will be looking for answers when it sits down with the utility no later than next week.

Hallstrom also confirmed that smoke emerging from a manhole a few blocks from the Scotia Street substation was connected to the power outage. A fuse had exploded when the utility suddenly pulled power from the other substation to restore electricity to the Back Bay, said Hallstrom.

Few customers complained. A half dozen restaurants in the neighborhood said they lost little to no inventory since the outage occurred in the middle of the night, leading to a sleepy Sunday when many businesses don’t open until noon.

Many residents also were unaware of the outage since they slept in on Sunday morning.

Hallstrom said NSTAR has invested $50 million to renovate the substation and work is expected to be completed in a couple of weeks, hopefully ensuring fewer problems in the future.